Such a circuit arrangement is known from International Patent Application WO 86/06572. Striations are formed in a low-pressure mercury discharge lamp (referred to hereinafter as the lamp) operated by the known circuit arrangement, i.e. alternating comparatively dark and comparatively light regions in the plasma of the lamp. The striations often move through the lamp. The direction in which and the velocity at which the striations move through the lamp depend both on the ratio between amplitude A1 and amplitude A2 and on the amplitude and polarity of the DC component G. This renders it possible to adjust the speed with which striations move through the lamp by using the asymmetry device and/or the DC device. The known circuit arrangement thus offers the possibility, for example, of making striations substantially stationary in the lamp, which may be desirable, for example, in lamps which are used for advertising purposes. A second possibility of the known circuit arrangement is to use the asymmetry device and/or DC generating device for making the velocity of the striations so great that the human eye is substantially incapable of observing them any more. As a result, it appears to an observer that the brightness in the lamp is substantially uniform, and that objects in the vicinity of the lamp are evenly illuminated. These two effects of the second possibility are desirable in the majority of practical applications of the lamp, i.e. that it is substantially always desirable to render striations in the lamp invisible. Factors which influence the occurrence of striations are inter alia the ambient temperature of the lamp, the power consumed by the lamp, and the composition of the lamp plasma. It has been found that it is not or substantially not possible under unfavorable conditions to render striations invisible through the exclusive use of the asymmetry device II or the DC generating device. Since the known circuit arrangement is provided with both the asymmetry device and the DC generating device, it is possible in principle to influence the velocity with which striations move through the lamp more strongly than would be possible with a circuit arrangement which is provided only with a device for generating a DC component of the lamp current or which is provided only with a device for rendering an amplitude of a high-frequency alternating current through the lamp in a first polarization direction and an amplitude of the high-frequency alternating current in a second polarization direction unequal to one another. It was found, however, that the effect on the velocity with which the striations moved achieved by the asymmetry device II is in practice often opposed to the effect achieved by the DC generating device. The result of this is that, in spite of the combined use of the asymmetry device and the DC generating device, it is hardly possible to render striations invisible, and the known circuit arrangement functions ineffectively.